Balancing the ventricular outputs of pulsatile total artificial hearts

Background: Maintaining balanced left and right cardiac outputs in a total artificial heart (TAH) is challenging due to the need for continuous adaptation to changing hemodynamic conditions. Proper balance in ventricular outputs of the left and right ventricles requires a preload-sensitive response and mechanisms to address the higher volumetric efficiency of the right ventricle. Methods: This review provides a comprehensive overview of various methods used to balance left and right ventricular outputs in pulsatile total artificial hearts, categorized based on their actuation mechanism. Results:Reported strategies include incorporating compliant materials and/or air cushions inside the ventricles, employing active control mechanisms to regulate ventricular filling state, and utilizing various shunts (such as hydraulic or intra-atrial shunts). Furthermore, reducing right ventricular stroke volume compared to the left often serves to balance the ventricular outputs. Individually controlled actuation of both ventricles in a pulsatile TAH seems to be the simplest and most effective way to achieve proper preload sensitivity and left–right output balance. Pneumatically actuated TAHs have the advantage to respond passively to preload changes. Conclusion: Therefore, a pneumatic TAH that comprises two individually actuated ventricles appears to be a more desirable option—both in terms of simplicity and efficacy—to respond to changing hemodynamic conditions.</p

Letters to the Editor

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65933/1/j.1528-1157.1995.tb00479.x.pd

Photodynamic therapy for Barrett's oesophagus with use of 5-aminolevulinic acid

Barrett's oesophagus is a premalignant lesion of the oesophagus characterized by the presence of colunmar epithelium with intestinal metaplasia in the distal oesophagus. Oesophageal adenocarcinoma (the most rapidly increasing cancer in the Western world) is thought to originate from Barrett's oesophagus following a sequence from metaplasia through dysplasia to adenocarcinoma. To gain insight in the various aspects of Barrett's oesophagus, the state of the art of its pathophysiology, diagnosis and management is reviewed in Chapter 1, Part I, the general introduction of the thesis. Both endoscopic surveillance and oesophageal resection are recommended for patients with Barrett's oesophagus and high-grade dysplasia. Tins, however, is still controversial as the mortality and morbidity associated with oesophageal resection are considered to be high in view of a preneoplastic disease. Therefore, endoscopic ablation therapies, including photodynamic therapy, have been experimentally used to treat Barrett's oesophagus. The characteristics of the various endoscopic ablation therapies and their results are summarized in Chapter 2. The studies described in this thesis aim at making 5-aminolevulinic acidmediated photodynamic therapy clinically applicable for the endoscopic treatment of Barrett's oesophagus. For a better understanding of the experinlental chapters, Part I is completed with Chapter 3, outlining the fundamentals of 5-aminolevulic acid-based photodynamic therapy

Measuring what matters to the patient: health related quality of life after aortic valve and thoracic aortic surgery

With improved outcomes following cardiac surgery, health related quality of life (HRQoL) gains increasing importance for the better judgement of choosing the preferred treatment strategy in the individual patient. The physician perception of patient preferences can differ considerably from actual patient preferences, underlining the importance of gathering evidence of actual patient preferences before and quality of life after cardiac surgery. The objective of the current review is to provide an overview of current insights into the quality of life measurements after aortic valve and thoracic aortic surgery and to provide starting points for the application of HRQoL measurements toward the future. The amount and level of evidence on HRQoL outcomes after aortic valve and thoracic aortic surgery seems to be insufficient. Little has been investigated about the natural course of HRQoL after cardiac surgery, HRQoL outcomes between different surgical strategies, HRQoL outcomes between surgical patients and the general population, the different factors influencing HRQoL after cardiac surgery, and the effect of HRQoL on healthcare costs. More prospective studies should be performed, taking into account the knowledge gaps that need to be filled. Computerized adaptive testing methods through open source programs can be implemented to keep the burden to the patient as low as possible and catalyze the use of these tools. Our cardiovascular surgery community has the responsibility to deliberate how it can proceed to effectively fill in these knowledge gaps, and use this newfound knowledge to improve shared treatment decision making, patient outcomes, and ultimately optimize health care efficiency